From c9e42158d6a770b4e1a74e89e4ae65cc56a6330f Mon Sep 17 00:00:00 2001
From: littensy <56808540+littensy@users.noreply.github.com>
Date: Tue, 5 May 2026 21:24:04 -0700
Subject: [PATCH] test: add multi benchmark

---
 benches/multi.luau | 188 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 188 insertions(+)
 create mode 100644 benches/multi.luau

diff --git a/benches/multi.luau b/benches/multi.luau
new file mode 100644
index 0000000..6c8235c
--- /dev/null
+++ b/benches/multi.luau
@@ -0,0 +1,188 @@
+local Charm = require("../packages/charm/src")
+local bench = require("./bench")
+
+type Atom<T> = Charm.Atom<T>
+
+local signal = Charm.atom
+local computed = Charm.computed
+local effect = Charm.effect
+
+local function busy(): number
+	local a = 0
+	for i = 1, 100 do
+		a += 1
+	end
+	return a
+end
+
+do
+	local head = signal(0)
+	local computed1 = computed(function()
+		return head()
+	end)
+	local computed2 = computed(function()
+		computed1()
+		return 0
+	end)
+	local computed3 = computed(function()
+		busy() -- heavy computation
+		return computed2() + 1
+	end)
+	local computed4 = computed(function()
+		return computed3() + 2
+	end)
+	local computed5 = computed(function()
+		return computed4() + 3
+	end)
+	effect(function()
+		computed5()
+		busy() -- heavy side effect
+	end)
+
+	bench.run("avoidablePropagation", function()
+		head(1)
+		assert(computed5() == 6)
+		for i = 0, 999 do
+			head(i)
+		end
+		assert(computed5() == 6)
+	end)
+end
+
+do
+	local head = signal(0)
+	local double = computed(function()
+		return head() * 2
+	end)
+	local inverse = computed(function()
+		return -head()
+	end)
+	local current = computed(function()
+		local result = 0
+		for i = 0, 19 do
+			result += if head() % 2 == 1 then double() else inverse()
+		end
+		return result
+	end)
+
+	local callCounter = 0
+	effect(function()
+		current()
+		callCounter += 1
+	end)
+
+	bench.run("unstable", function()
+		head(1)
+		assert(current() == 40)
+		callCounter = 0
+		for i = 0, 99 do
+			head(i)
+		end
+		assert(callCounter == 100)
+	end)
+end
+
+do
+	local head = signal(0)
+	local double = computed(function()
+		return head() * 2
+	end)
+	local inverse = computed(function()
+		return -head()
+	end)
+	local current = computed(function()
+		local result = 0
+		for i = 0, 19 do
+			result += if head() % 2 == 1 and i % 2 == 1 then double() else inverse()
+		end
+		return result
+	end)
+
+	local callCounter = 0
+	effect(function()
+		current()
+		callCounter += 1
+	end)
+
+	bench.run("unstable 50%", function()
+		head(1)
+		assert(current() == 10)
+		callCounter = 0
+		for i = 0, 99 do
+			head(i)
+		end
+		assert(callCounter == 100)
+	end)
+end
+
+do
+	local head = signal(0)
+	local last: () -> number = head
+	local callCounter = 0
+
+	for i = 0, 49 do
+		local current = computed(function()
+			return head() + i
+		end)
+		local current2 = computed(function()
+			return current() + 1
+		end)
+		effect(function()
+			current2()
+			callCounter += 1
+		end)
+		last = current2
+	end
+
+	bench.run("broadPropagation", function()
+		head(1)
+		callCounter = 0
+		for i = 0, 49 do
+			head(i)
+			assert(last() == i + 50)
+		end
+		assert(callCounter == 50 * 50)
+	end)
+end
+
+do
+	local heads = {}
+	for index = 0, 99 do
+		heads[index] = signal(0)
+	end
+
+	local mux = computed(function()
+		local result = {}
+		for index = 0, 99 do
+			result[index] = heads[index]()
+		end
+		return result
+	end)
+
+	local splited = {}
+	for index = 0, 99 do
+		local x = computed(function()
+			return mux()[index]
+		end)
+		splited[index] = computed(function()
+			return x() + 1
+		end)
+	end
+
+	for _, x in splited do
+		effect(function()
+			x()
+		end)
+	end
+
+	bench.run("mux", function()
+		for i = 0, 9 do
+			heads[i](i)
+			assert(splited[i]() == i + 1)
+		end
+		for i = 0, 9 do
+			heads[i](i * 2)
+			assert(splited[i]() == i * 2 + 1)
+		end
+	end)
+end